The object of the invention is a metal rope, an elevator provided with the metal rope and the use of the lubricant for lubricating the metal rope.
Ropes laid from metal wires, more particularly the hoisting ropes, i.e. suspension ropes, of elevators or other hoisting apparatuses are generally lubricated with some suitable lubricant. Lubrication improves the operation of ropes and reduces the wearing of the ropes, in which case the service life of the ropes lengthens. Lubrication also prevents the rusting of ropes. Ropes are usually lubricated in connection with the manufacture of the ropes, e.g. such that lubricant is sprayed into the strand to be manufactured when laying the strands of ropes from steel wires.
According to one prior-art technique, the lubricant used is paraffin-based. A problem when using paraffin is, however, when the ropes get hot the structure of the oil thins, in which case the oil bound by the paraffin can easily detach from the rope. Another problem with paraffin-based lubricant is that the traction sheave-rope contact becomes more slippery at a higher temperature, due to which it can be difficult to get the friction factor between the traction sheave and the rope to meet the values required by elevator regulations. If the friction factor is too small, the ropes can slip on the traction sheave, which causes problems and can also be a safety risk. Other relatively thin lubricants have the same type of problems as oil mixed with paraffin.
Normally it is desired to make elevators and elevator structures as light as possible, in which case the elevator would be cheaper to manufacture and install. As the elevator car and the counterweight become lighter, however, the friction between the elevator ropes and the traction sheave decreases at the same time. The reduction in friction thus limits the making of lighter elevators; a general aim is to achieve high friction but, however, such that the ropes do not wear too quickly.